客体同维度特征的视觉工作记忆存储机制

客体理论认为视觉工作记忆的存储单位是客体, 人类能够把组成物体的所有特征整合成一个单元进行记忆, 不管这些特征是来自不同维度还是同一维度。然而同一维度多个特征可以被整合成客体记忆的结果只被少数研究证实, 大量研究发现同一维度的多个特征不能被整合记忆, 这形成了弱客体理论的基本观点。为了解决两大理论之间的争议, 本研究主要探究同维度特征能否被整合记忆。通过分析以往研究, 我们认为实验范式和物体意义两个因素可能是导致之前大部分研究没有发现维度内特征能够被整合记忆的原因。因此, 实验1采用回忆报告范式替代以往研究经常使用的变化觉察范式, 结果发现, 同一维度的多个特征难以被整合记忆。实验2以记忆无意义物体的特征为基线, 探究在记忆有意义物体的特征时是否可能将多个特征进行整合记忆。结果发现, 对于有意义物体的特征的记忆成绩并没有显著好于记忆无意义物体特征的成绩, 说明即使采用具有较强整合线索的有意义物体作为载体, 同一维度多个特征也难以被整合记忆。两个实验结果进一步支持了弱客体理论。

Storage mechanism of same-dimension features in visual working memory

Although visual working memory (VWM) has been studied for decades, the storage mechanism of VWM remains unclear. A strong object-based theory and a weak object-based theory have been proposed for the VWM storage mechanism. The arguments of these two theories focus on whether features from the same dimension can be integrated into the representation of objects stored in VWM. The strong object-based theory claimed that object was a unit of VWM, the capacity of which was not affected by the number of features. However, the recent studies have proved that weak object-based theory because the features from the same dimension (e.g., two colors) cannot be integrated simultaneously into the representation of objects in VWM, and the VWM capacity was constrained by the number of features. The aim of this paper is to explore whether features from the same dimension can be successfully integrated into a representation of objects stored in VWM. Based on the finding of previous study, we proposed that experimental paradigm and stimulus property might be the main factors that influence the integration of same-dimension information into a representation. Two experiments were conducted to test whether these two factors could affect the integration process respectively. Experiment 1 used a recall task to investigate whether experimental paradigm is a main factor to influence the integration of same-dimension features. The results show that, no matter which experimental paradigms, participants were unable to integrated the same-dimension features into a representation. These suggests that experimental paradigm is not a main factor for explaining the failure of the integration of same-dimension features into a representation stored in VWM. Experiment 2 was conducted to explore whether stimulus property could affect the integration of same-dimension features. Two types of stimulus were selected as experimental materials (e.g., meaningless and meaningful objects). We expected that, in meaningful object condition, participants would easily memorize two conjoint colors as one representation because of the integrated clues (the meaningful shapes); in contrast, participants were more likely to memorize the two features separately due to the absence of integrated clues. The results of Experiment 2 show that, the same-dimension features could not be integrated into one representation in both conditions (meaningful and meaningless objects). Thus, Experiment 2 suggests that the same-dimension features could not be integrated into a representation of objects stored in VWM, regardless of the integrated clues. The present study provides supporting evidences for the weak object-based theory by claiming that manipulation of variables such as experimental paradigm and stimulus property exerts no effect on the memorization of same- dimensional features.